Over the course of the river system. Many different types of landforms can be formed.$^{10}$
Due to the high velocity nature of the river at this stage, there tends to be an increase in vertical erosion. As a result of hydraulic action and abrasion, the river can cut a deep channel.$^{10}$
In isolation, this would create acute and perfect V-shaped valleys. However, due to surface run-off, soil creep, and other mass movements, the valley sides are less pronounced. Other weathering processes may result in the further breakdown of the valley sides.$^{10}$
Another difference is that there may be obstacles in the path of the river. For example, densely rooted soil. Because water always follows the path that requires the least energy, the river will go around the obstacle. This forms what are called interlocking spurs.$^{10}$
In the upper course, the edges of the rivers are very rough. When there is a large enough object that is strong enough to resist the strength of the river, potholes may form behind it. This is because when the water flows over it, the flow becomes turbulent and eddies are formed. These turbulent flow will begin to erode the river bed right behind the rock, overtime resulting in small depressions.$^{10}$
Rivers, in the upper course, may have localized rapid increase in gradient. This results in a larger river velocity in that part of the river. Rapids, as they are called, are also characterized by the extremely turbulent flow. This is also called as white water as the water appears white as a result of the turbulent flow.$^{10}$
During the middle course of the river, the discharge increases. Eventually the discharge will exceed the capacity of the river channel. Hence, the water will overflow onto the river banks. This is the floodplain.$^{10}$
As rivers grow increasing sinuous during its middle course, it may eventually meander. A meandering river is one where the river takes large sweeping loops and turns. The specific reasons involve a combination of intrinsic and extrinsic factors. As a result of these factors, the neck of the meander may get narrower and narrower until the river cuts through it. Once this happens an ox bow lake is formed.$^{10}$
River deltas are formed at the mouth of the river or inland on the approach to the mouth. The exact shape is dependent on the specific interactions between the fluvial and marine systems. However, there are three kinds of deltas, accurate, cuspate, and birdfoot(in this order in the diagram).$^{10}$
Accurate deltas are characterized by the gentle curving of the coastline. They have a specific pattern of branching distributaries. Birdfoot deltas have fewer distributaries. Cuspate deltas generally have a tooth-like form.$^{10}$